Balancing late-progression gestalt in a single-classed game?

[Umbral Reaver]

How would you feel about a feat such as this existing?
Would it be appropriate at any level requirement?

Comments are welcomed.

Gestalt
You have blended your studies in two disparate areas skilfully.
Prerequisites: At least four levels of one base class and four levels of another base class.
Benefit: When you take this feat, choose two base classes you have at least four levels in. After this level, whenever you gain a level in one of these classes, you gain the BAB progression of the class of your choice (this choice cannot be changed), and choose the Reflex, Fortitude and Will save, hit die and skill ranks per level similarly. You gain the class features of both classes, as if you had gained a level in each of them. If these classes share a class feature, it does not stack and you must choose which class you gain it from.

[TriOmegaZero]

Waiting until level 8 might be a bit much. Make it three levels in both classes and you pretty well have the requirements for most Mystic Theurge-style classes. I get the feeling that single-classed characters in a game allowing this feat would be exceptionally rare however.

[Umbral Reaver]

Technically as written, the first gestalt level would be at 10 (taking the feat at 9).

The idea with this was 'what if Mystic Theurge was a feat?'.

[TriOmegaZero]

Well, as written it definitely favors martial characters over casters, since a dual-caster would be behind four/five levels in both spell progressions. Meanwhile, a fighter/wizard would gain 16th level casting with only a minor hit to BAB.

[Umbral Reaver]

Is that a bad thing? ;)

[TriOmegaZero]

Depends on your style of play. :)

[Viktyr Korimir]

Every time I propose something like this, I get chewed out.

I say go for it.